It's funny to me that so many of you are willing to give her a pass because she is attractive and would not have an issue getting someone her age. But, if she were less attractive or it were a male you seem more incline to believe that power of authority could have been used. Fundamentally this is an abuse of power regardless of looks.
Isn't the abuse of power an issue even with college professors and students? It isn't just an age of consent issue for high school. Schools must have policies and are certainly not going to deal with this on a case-by-case basis in advance. Many companies and departments have policies regarding co-workers and certainly regarding supervisors and direct reports.